Generally, in the field of production of patterned structures, it is known to control the process of pattern creation by one or more of integrated, in-situ, and stand alone optical measurement techniques.
For example, U.S. Pat. No. 6,764,379, assigned to the assignee of the present application, describes the use of integrated technique and also a combination of the integrated and in-situ techniques for monitoring the processing of a stream of substantially identical articles progressing on a production line. First, an in-situ technique is applied to identify and terminate the processing upon detecting an end-point signal, where the latter corresponds to a predetermined value of a certain parameter of the article being processed. Upon completing the processing in response to the end-point signal, generated by an end-point detector continuously operating during the processing of the article, integrated monitoring is applied to the processed article to measure the value of said parameter. The measured value of the desired parameter is analyzed to determine a correction value to be used for adjusting the end-point signal to be used for properly terminating the processing of the next article in the stream.